The field of the present invention is mechanisms for indexing mechanical devices such as transmissions.
A wide variety of devices have long been available for mechanical engagement of rotating components. Where such engagement is to occur with the elements rotating, a variety of coupling mechanisms are frequently employed. In vehicle transmissions, clutches, fluid couplings, friction bands and synchronizing rings are typical. In many circumstances, these devices are quite adequate. However, many such devices are subject to power loss, rapid wear, lack of sufficient engaging strength and lack of sufficient engaging speed.
Mechanisms for automatically locking rotating components have been employed which provide rapid engagement, very substantial engaging strength, and extended wear. One such device is a roller clutch which employs an engagement inner having an inner race, an engagement outer having an outer race and rollers therebetween. One of the two races has cam surfaces which are inclined relative to the other race. The rollers are set within a cage which generally rotates with the cam surfaces. A slight rotation of the cage relative to the cam surfaces results in selected engagement or disengagement of the inner and outer elements through wedging or releasing of the rollers. Such a roller clutch is disclosed in U.S. Pat. No. 3,283,611 to Weismann et al., entitled Positive Drive Differential. The disclosure of the Weismann et al. patent is incorporated herein by reference.
In the Weismann et al. patent, automatic disengagement of the mechanisms occurs when differential speeds are experienced by the mechanism. However, employment of such a roller cam engagement mechanism with selective engagement and disengagement in transmission applications has alluded practical utility. Proper control of the cage such that it will remain properly oriented relative to the cam surfaces and yet remain selectively controllable for engagement and disengagement has proven difficult. In transmission applications, the control of multiple engagement mechanisms becomes critical as simultaneous engagements can be catastrophic and yet very rapid shifting is desired.
Transmissions employing roller clutches such as disclosed in the Weismann et al. patent referenced above are known to employ indexing drive mechanisms in association with linkage engageable between the indexing drive and clutch control elements. Such devices are disclosed in U.S. Pat. No. 4,817,451 to Weismann, U.S. Pat. No. 4,987,790 to Weismann and U.S. Pat. No. 5,131,285 to Weismann et al., the disclosures of which are incorporated herein by reference. In the Weismann et al. ""285 patent, a motor operating as a servomotor drives a pinion and rack gear, the motor acting as an indexing drive. An actuator with slots therein is longitudinally fixed to the rack and is free to rotate relative to the rack. The actuator in turn controls the position of pins which control gear engaging clutches. With the exception of the indexing drive of this disclosed transmission, the details as disclosed in the Weismann et al. ""285 patent are contemplated as one possible combination with the indexing drives of the present disclosure.
The present invention is directed to an indexing drive and its combination with multiple ratio power transmission systems. The indexing drive includes actuators slidably mounted in guideways extendible to a carrier including follower elements. Concavities and convexities on the actuators and the carrier cooperate to perform an indexing function.
In a first separate aspect of the present invention, the indexing drive is configured with the housing and the actuators such that the concavities are spaced one from another and the convexities are spaced one from another so that when one of the concavities is fully engaged with one of the convexities, another of the concavities and another of the convexities are sufficiently aligned to be partially engageable. This allows the indexing drive to be set up such that the actuators can drive the carrier in at least one direction.
In a second separate aspect of the present invention, the indexing drive of the first aspect may further include that two sets of convexities and concavities are partially engageable with another set being fully engaged. This allows a selective driving of the carrier in two directions.
In a third separate aspect of the present invention, the indexing drive includes actuators slidably mounted in guideways which include drive elements extendible to follower elements on a carrier. The drive elements of the actuator are mutually parallel while the carrier includes a surface which is circular in plan and includes concavities of the follower elements therein. This configuration provides for a compact design and one which provides uniform moment arms through which the drive elements drive the carrier.
In a fourth separate aspect of the present invention, the indexing drive includes actuators slidably mounted in guideways which include drive elements extendible to follower elements on a carrier. The follower elements of the carrier define a cylindrical surface with concavities therein. The carrier is rotatably mounted. The guideways which receive the actuators include longitudinal centerlines which intersect the rotational axis of the carrier. Rotational indexing is thus provided.
In a fifth separate aspect of the present invention, the indexing drive includes actuators slidably mounted in guideways which include drive elements extendible to follower elements on a carrier. The carrier is linearly movable to index linearly rather than rotationally. Guideways carrying the actuators include longitudinal centerlines which again intersect the carrier. Rack and pinion gearing is not necessary with such longitudinal indexing.
In a sixth separate aspect of the present invention, the indexing drive includes actuators slidably mounted in guideways which include drive elements extendible to follower elements on a carrier. The actuators of the foregoing aspects may be driven by a number of devices. Among others, pressurized fluid is contemplated as well as electromagnetic coils. In the case of pressurized fluid, solenoid valves may be employed to selectively activate the actuators. Pneumatics may be used. A controller can be employed for actuating either the magnetic coils or the solenoid valves. Semiautomatic as well as automatic selection is thereby possible through such a controller.
In a seventh separate aspect of the present invention, the indexing drive of any of the foregoing aspects is contemplated to be employed in association with a transmission. Transmission gears are engaged through clutches which are driven by clutch control elements. Linkage engages the clutch control elements with the indexing drive. With the present indexing systems, rapid, accurate and exclusive engagement and disengagement of gear wheels with a shaft are possible.
In an eighth separate aspect of the present invention, combinations of the foregoing separate aspects are contemplated.
Accordingly, it is an object of the present invention to provide improved indexing and power transmission mechanisms. Other and further objects and advantages will appear hereinafter.